The present chapter is mainly allocated to the in-depth study of Cultural Linguistics of friendship in locally produced English textbooks for Iranian ELT institutes as specifically practiced at a state-run language institute. The researchers employed the Cultural Linguistics methodology with a multimodal-semiotic perspective to analyze the cultural conceptualizations embedded across texts, tasks, and visuals. In practice, the contents presented in the three student books developed for the advanced level were studied to see how the linguistic encoding of culture (i.e., linguistic expressions) and the cultural grounding of language (i.e., cultural artifacts) manifested cultural conceptualizations of the concept of friendship. Unveiling a few instances of variations in cultural realizations of friendship, the findings of the present study revealed that the contents of ELT textbooks used at the state-run language institute were relatively devoid of pluralistic culture pedagogy, cultural diversity, and cultural dialogism. They promoted a rather biased, Anglo-English cultural ‘monologism’ which fully contrasts with the English as an International Language paradigm.